This invention relates to a hoist for use at a manhole of the type which can be used for raising and lowering the person entering the hole.
Recent safety legislation has mandated that it is necessary for persons entering manholes to be attached to a suitable hoist so that they can be recovered in the event of any difficulties being encountered, for example poisonous fumes which can accumulate in underground locations of this type.
A tripod hoist is available which includes three legs which stand at angularly spaced locations around the hole and converge to a central apex from which a cable descends into the manhole. This device however is generally unsatisfactory for a number of reasons, including the high initial cost, the unsatisfactory balancing condition and the obstruction of the manhole by the equipment which can interfere with the person or other equipment being passed through the hole. It is one object of the present invention, therefore, to provide an improved hoist of this general type. In addition various hoist type equipment is available for use in various different circumstances. Thus devices are proposed for use with lifting patients from a wheelchair and in lifting engines from an engine compartment of an automobile. However none of these devices is suitable for use at a manhole and it has been necessary for the present inventor to design a device which is specifically suited and adapted for the particular purpose of use as a hoist at a manhole.